#include<iostream>

#include<string>

#include<stdio.h>

#include<algorithm>

#include<cstring>

#include<cstdio>

#include <math.h>

using namespace std;

int a;

char b[];

float s;

int main(){

    scanf("%d %s",&a,b);

    //printf("%s\n",b);

    int len = strlen(b);

    s= ;

    for(int i =  ; i < len ; i++)

    {

        int t = ;

        if(b[i] >= 'A')

            t = b[i] -'A' + ;

        else

            t = b[i] - '';

        s += pow(a,-i+) * t;

    }

    s *= ;

    s = floor(s + 0.5);

    s /= ;

    printf("%0.4f\n",s);

    //printf("%s\n",a);

    return ;

}